A variety of trailer tongues and devices (generically referred to as jacks) for raising and lowering same are known. The design shown in FIG. 1 is a straight telescoping tubular jack and is very widely known. The telescoping member can be significantly retracted thereby resulting in substantially vertical movement of the trailer's hitchball coupler. However, as shown in FIG. 2, even when fully retracted, the telescoping member 2 hangs below the tongue. This design can be modified so that the telescoping member 2 can be rotated to horizontal position when not in use. One drawback associated with these designs is that bending damage can occur if the jack is not fully retracted and/or rotated to the horizontal position before towing. Damage can result when the telescoping tube or the contact foot, hanging below the tongue, strikes an object, such as a curb, or drags over uneven terrain.
In FIG. 3, another well known design is shown. In this design, a pivoting support leg 4 is used in combination with a screw jack 6 in an attempt to prevent the possible occurrence of bending damage. The pivoting support leg 4 is angled such that it deflects impacts when less than fully retracted. The fixed pivot pin 8 at the forward end of the pivoting leg 4 allows that the jack 6 itself may be pivotally mounted at each of its ends, with the lower end following the pivoting leg 4 through the arc of its vertical movement. This relieves the jack 6 entirely of all bending loads that may otherwise cause damage as described above.
One particular disadvantage of the pivoting leg 4 is that vertical movement of the hitchball coupler 9 follows an arc (designated A1 in FIG. 3), dictated by the length of the pivot leg itself, which includes a significant horizontal component. This is undesirable because of the difficulty it imposes on attachment of the coupler 9 to the towing vehicle hitchball 7. For example, after care is taken to line up the hitchball of the towing vehicle directly under the raised coupler 9, the jack 6 handle is rotated, thereby retracting the pivoting leg 4 and lowering the coupler 9. As it is lowered, due to its arcuate motion, the coupler 9 pitches forward, therefore, often times, requiring additional movement of the towing vehicle or trailer to re-align the hitchball 7 and coupler 9.
A long felt need exists for a device that is less susceptible to bending damage and substantially reduces the horizontal component of movement of the hitchball coupler when being lowered or raised.